Summary This allows you to make customized dowel centers. . USAGE: (See numbered pics.) 1) When assembling a wood project with dowels, drill the holes on one piece, then insert these. 2) Press the mating piece together and it will give you perfectly-aligned marks for drilling the other side. 3) Integrated lip makes it easy to remove with a flat-head screwdriver. 4) Drill the holes on the marks, and glue together. . Common sizes are available in the attached stl files.